| 摘要 |
PURPOSE:To display and warn it to the user that normal operations cannot be ensured when the temperature of a watch becomes lower than a preset level by effecting the display different from the normal one at the preset temperature which is detected by a temperature sensor composed of a thermister. CONSTITUTION:When a sampling PMOS transistor 2 is rendered conductive by sampling pulses, a through current flows through a temperature sensor 1. At a normal temperature, the resistance of the sensor 1 is sufficiently high, and the potential at point a at that time is preset at ''1'' level. A NOR gate 4 always feeds a ''0'' level to the base terminal of a driver 5, and this driver 5 is rendered inconductive so that a light emitting diode 6 emits no light. At a low temperature, the resistance of the sensor 1 is lowrerd, and the potential at the point a is preset at the ''0'' level, which is generated at the NOR gate 4. Since this NOR gate 4 feeds the ''1'' level to the base electrode of the driver 5 only when the sampling pulses take the ''0'' level, the light emitting diode 6 flashes for the period of the sampling pulses to warn the low temperature to the user. |
